PML_V2 global evapotranspiration and gross primary production (2000.02-2023.12)

Summary

This data is an 8-day 5km (0.05°) data aggregated from the latest 8day 500m PML-V2 global evapotranspiration and gross primary production data in Google Earth Engine, available since 2000.2.26 to 2023 (latest and will update annually).

Notes

• 8-day means an average of the variable for the 8 days (xx d-1).

• Land evapotranspiration (ET) can be computed as a sum of Ec, Ei, and Es, while in water, Penman evapotranspiration denotes actual evaporation (ET_water).

• In a 5km resolution, please do not add ET_water to land ET as they represent a different coverage of area within the 5km pixel. Please see the coverage ratio file for each variable.

Changes

Here, this PML-V2 dataset denotes the latest update that follows the original implementation of Zhang et al., 2019, except with Terra LAI for longer temporal coverage and annual updates.

• Temporal coverage lengthened to 2000.2-2023.12

• Using MODIS Terra LAI (MOD15A2H) with original wWhd smoother processing as in Kong et al., 2019

• Recalibrated with the new MODIS Terra LAI

• Other climatic forcing and MODIS input remain the same

Google Earth Engine

Original 500m 8-day data in GEE

https://developers.google.com/earth-engine/datasets/catalog/CAS_IGSNRR_PML_V2_v018

Methods

Penman-Monteith-Leuning Evapotranspiration V2 (PML_V2) products include evapotranspiration (ET), its three components, and gross primary product (GPP) at 500m and 8-day resolution during 2000-2017 and with spatial range from -60°S to 90°N. The major advantages of the PML_V2 products are:

1. coupled estimates of transpiration and GPP via canopy conductance (Gan et al., 2018; Zhang et al., 2019)

2. partitioning ET into three components: transpiration from vegetation, direct evaporation from the soil and vaporization of intercepted rainfall from vegetation (Zhang et al., 2016).

The PML_V2 products perform well against observations at 95 flux sites across globe, and are similar to or noticeably better than major state-of-the-art ET and GPP products widely used by water and ecology science communities (Zhang et al., 2019).

References

• Zhang, Y., Kong, D., Gan, R., Chiew, F.H.S., McVicar, T.R., Zhang, Q., and Yang, Y., 2019. Coupled estimation of 500m and 8-day resolution global evapotranspiration and gross primary production in 2002-2017. Remote Sens. Environ. 222, 165-182, doi:10.1016/j.rse.2018.12.031

• Gan, R., Zhang, Y.Q., Shi, H., Yang, Y.T., Eamus, D., Cheng, L., Chiew, F.H.S., Yu, Q., 2018. Use of satellite leaf area index estimating evapotranspiration and gross assimilation for Australian ecosystems. Ecohydrology, doi:10.1002/eco.1974

• Zhang, Y., Peña-Arancibia, J.L., McVicar, T.R., Chiew, F.H.S., Vaze, J., Liu, C., Lu, X., Zheng, H., Wang, Y., Liu, Y.Y., Miralles, D.G., Pan, M., 2016. Multi-decadal trends in global terrestrial evapotranspiration and its components. Sci. Rep. 6, 19124. doi:10.1038/srep19124